Add String and MarshalJSON methods to Payload type

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `Payload.String() string`  method is added
+- `Payload.MarshalJSON() ([]byte, error)` method is added
+
 ## [0.12.0] - 2020-09-12
 
 **IMPORTANT**: If you are upgrading from a previous version, please install the latest version of the CLI `go get -u github.com/hibiken/asynq/tools/asynq` and run `asynq migrate` command. No process should be writing to Redis while you run the migration command. 

payload.go

@@ -44,6 +44,16 @@ func toInt(v interface{}) (int, error) {
 	}
 }
 
+// String returns a string representation of payload data.
+func (p Payload) String() string {
+	return fmt.Sprint(p.data)
+}
+
+// MarshalJSON returns the JSON encoding of payload data.
+func (p Payload) MarshalJSON() ([]byte, error) {
+	return json.Marshal(p.data)
+}
+
 // GetString returns a string value if a string type is associated with
 // the key, otherwise reports an error.
 func (p Payload) GetString(key string) (string, error) {

payload_test.go

@@ -6,6 +6,7 @@ package asynq
 
 import (
 	"encoding/json"
+	"fmt"
 	"testing"
 	"time"
 
@@ -645,3 +646,30 @@ func TestPayloadHas(t *testing.T) {
 		t.Errorf("Payload.Has(%q) = true, want false", "name")
 	}
 }
+
+func TestPayloadDebuggingStrings(t *testing.T) {
+	data := map[string]interface{}{
+		"foo": 123,
+		"bar": "hello",
+		"baz": false,
+	}
+	payload := Payload{data: data}
+
+	if payload.String() != fmt.Sprint(data) {
+		t.Errorf("Payload.String() = %q, want %q",
+			payload.String(), fmt.Sprint(data))
+	}
+
+	got, err := payload.MarshalJSON()
+	if err != nil {
+		t.Fatal(err)
+	}
+	want, err := json.Marshal(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if diff := cmp.Diff(got, want); diff != "" {
+		t.Errorf("Payload.MarhsalJSON() = %s, want %s; (-want,+got)\n%s",
+			got, want, diff)
+	}
+}